The present invention relates to a device for adjusting the degree of opening of the throttle valve of a carburetor.
In order to promote engine warm-up, a carburetor has been known which comprises a lever fixed onto the valve shaft of the throttle valve, a cam engaging with the tip of the lever and retaining the throttle valve at the fast idling position, and a cam actuating device for rotating the cam about the rotating axis thereof in response to a change in the engine temperature. In this carburetor, the throttle valve is gradually closed by rotating the cam in accordance with an increase in the engine temperature. In such a conventional carburetor, since the degree of opening of the throttle valve has a great influence on the engine operation during engine warm-up, it is necessary to adjust the throttle valve so that the degree of opening of the throttle valve when the carburetor is assembled to the engine becomes precisely equal to a predetermined fast idling degree.
During engine warm-up, however, the engine temperature and the engine cooling water temperature continuously rise. Under such conditions, it is difficult in practice to adjust the degree of opening of the throttle valve to the degree appropriate to, for example, the engine cooling water temperature.
Contrary to this, when the engine warm-up is completed, the engine operation becomes stable. If the throttle valve were then opened to the fast idling position and the degree of opening of the throttle valve were then adjusted so that the engine speed became equal to the predetermined speed, it would be possible precisely to adjust the fast idling degree of the throttle valve uniformly for all engines. In a conventional carburetor, however, when the engine warm-up is completed, the cam is disengaged from the lever fixed onto the valve shaft of the throttle valve. Thus, it is impossible to adjust the fast idling degree of opening of the throttle valve.